Identification documents (hereafter “ID documents”) play a critical role in today's society. One example of an ID document is an identification card (“ID card”). ID documents are used on a daily basis—to prove identity, to verify age, to access a secure area, to evidence driving privileges, to cash a check, and so on. Airplane passengers are required to show an ID document during check in, security screening, and prior to boarding their flight. In addition, because we live in an ever-evolving cashless society, ID documents are used to make payments, access an ATM, debit an account, or make a payment, etc.
Many types of identification cards and documents, such as driving licenses, national or government identification cards, bank cards, credit cards, controlled access cards and smart cards, carry thereon certain items of information which relate to the identity of the bearer. Examples of such information include name, address, birth date, signature and photographic image; the cards or documents may in addition carry other variant data (i.e., data specific to a particular card or document, for example an employee number) and invariant data (i.e., data common to a large number of cards, for example the name of an employer). AlI of the cards described above will hereinafter be generically referred to as “ID documents”.
In the production of images useful in the field of identification documentation, it is oftentimes desirable to embody into a document (such as an ID card, drivers license, passport or the like) data or indicia representative of the document issuer (e.g., an official seal, or the name or mark of a company or educational institution) and data or indicia representative of the document bearer (e.g., a photographic likeness, name or address). Typically, a pattern, logo or other distinctive marking representative of the document issuer will serve as a means of verifying the authenticity, genuineness or valid issuance of the document. A photographic likeness or other data or indicia personal to the bearer will validate the right of access to certain facilities or the prior authorization to engage in commercial transactions and activities.
Identification documents, such as ID cards, having printed background security patterns, designs or logos and identification data personal to the card bearer have been known and are described, for example, in U.S. Pat. No. 3,758,970, issued Sep. 18, 1973 to M. Annenberg; in Great Britain Pat. No. 1,472,581, issued to G. A. O. Gesellschaft Fur Automation Und Organisation mbH, published Mar. 10, 1976; in International Patent Application PCT/GB82/00150, published Nov. 25, 1982 as Publication No. WO 82/04149; in U.S. Pat. No. 4,653,775, issued Mar. 31, 1987 to T. Raphael, et al.; in U.S. Pat. No. 4,738,949, issued Apr. 19, 1988 to G. S. Sethi, et al.; and in U.S. Pat. No. 5,261,987, issued Nov. 16, 1993 to J. W. Luening, et al. AlI of the aforementioned documents are hereby incorporated by reference.
The advent of commercial apparatus (printers) for producing dye images by thermal transfer has made relatively commonplace the production of color prints from electronic data acquired by a video camera. In general, this is accomplished by the acquisition of digital image information (electronic signals) representative of the red, green and blue content of an original, using color filters or other known means. These signals are then utilized to print an image onto a data carrier. For example, information can be printed using a printer having a plurality of small heating elements (e.g., pins) for imagewise heating of each of a series of donor sheets (respectively, carrying sublimable cyan, magenta and yellow dye). The donor sheets are brought into contact with an image-receiving element (which can, for example, be a substrate) which has a layer for receiving the dyes transferred imagewise from the donor sheets. Thermal dye transfer methods as aforesaid are known and described, for example, in U.S. Pat. No. 4,621,271, issued Nov. 4, 1986 to S. Brownstein and U.S. Pat. No. 5,024,989, issued Jun. 18, 1991 to Y. H. Chiang, et al. Each of these patents is hereby incorporated by reference.
Commercial systems for issuing ID documents are of two main types, namely so-called “central” issue (CI), and so-called “on-the-spot” or “over-the-counter” (OTC) issue.
CI type ID documents are not immediately provided to the bearer, but are later issued to the bearer from a central location. For example, in one type of CI environment, a bearer reports to a document station where data is collected, the data are forwarded to a central location where the card is produced, and the card is forwarded to the bearer, often by mail. Another illustrative example of a CI assembling process occurs in a setting where a driver passes a driving test, but then receives her license in the mail from a CI facility a short time later. Still another illustrative example of a CI assembling process occurs in a setting where a driver renews her license by mail or over the Internet, then receives a drivers license card through the mail.
Centrally issued identification documents can be produced from digitally stored information and generally comprise an opaque core material (also referred to as “substrate”), such as paper or plastic, sandwiched between two layers of clear plastic laminate, such as polyester, to protect the aforementioned items of information from wear, exposure to the elements and tampering. The materials used in such CI identification documents can offer the ultimate in durability. In addition, centrally issued digital identification documents generally offer a higher level of security than OTC identification documents because they offer the ability to pre-print the core of the central issue document with security features such as “micro-printing”, ultra-violet security features, security indicia and other features currently unique to centrally issued identification documents. Another security advantage with centrally issued documents is that the security features and/or secured materials used to make those features are centrally located, reducing the chances of loss or theft (as compared to having secured materials dispersed over a wide number of “on the spot” locations).
In addition, a CI assembling process can be more of a bulk process facility, in which many cards are produced in a centralized facility, one after another. The CI facility may, for example, process thousands of cards in a continuous manner. Because the processing occurs in bulk, CI can have an increase in efficiency as compared to some OTC processes, especially those OTC processes that run intermittently. Thus, CI processes can sometimes have a lower cost per ID document, if a large volume of ID documents are manufactured.
In contrast to CI identification documents, OTC identification documents are issued immediately to a bearer who is present at a document-issuing station. An OTC assembling process provides an ID document “on-the-spot”. (An illustrative example of an OTC assembling process is a Department of Motor Vehicles (“DMV”) setting where a driver's license is issued to person, on the spot, after a successful exam.). In some instances, the very nature of the OTC assembling process results in small, sometimes compact, printing and card assemblers for printing the ID document.
OTC identification documents of the types mentioned above can take a number of forms, depending on cost and desired features. Some OTC ID documents comprise highly plasticized polyvinyl chloride (PVC) or have a composite structure with polyester laminated to 0.5-2.0 mil (13-51 .mu.m) PVC film, which provides a suitable receiving layer for heat transferable dyes which form a photographic image, together with any variant or invariant data required for the identification of the bearer. These data are subsequently protected to varying degrees by clear, thin (0.125-0.250 mil, 3-6 .mu.m) overlay patches applied at the print head, holographic hot stamp foils (0.125-0.250 mil 3-6 .mu.m), or a clear polyester laminate (0.5-10 mil, 13-254 .mu.m) supporting common security features. These last two types of protective foil or laminate sometimes are applied at a laminating station separate from the print head. The choice of laminate dictates the degree of durability and security imparted to the system in protecting the image and other data.
FIGS. 1 and 2 illustrate a front view and cross-sectional view (taken along the A-A line), respectively, of an exemplary prior art identification (ID) document 10. In FIG. 1, the prior art ID document 1 includes a photographic image 12, a bar code 14 (which may contain information specific to the person whose image appears in photographic image 12 and/or information that is the same from ID document to ID document), variable personal information 16, such as an address, signature, and/or birthdate, and biometric information 18 associated with the person whose image appears in photographic image 12 (e.g., a fingerprint). Although not illustrated in FIG. 1, the ID document 10 can include a magnetic stripe (which, for example, can be on the rear side (not shown) of the ID document 10), and various security features, such as a security pattern (for example, a printed pattern comprising a tightly printed pattern of finely divided printed and unprinted areas in close proximity to each other, such as a fine-line printed security pattern as is used in the printing of banknote paper, stock certificates, and the like).
Referring to FIG. 2, the ID document 10 comprises a pre-printed core 20 (such as, for example, white PVC material) that is, for example, about 25 mil thick. The core 20 is laminated with a transparent material, such as clear PVC material 22, which, by way of example, can be about 1-5 mil thick. The composite of the core 20 and clear PVC material 22 form a so-called “card blank” 25 that can be up to about 30 mils thick. Information 26a-c is printed on the card blank 25 using a method such as Dye Diffusion Thermal Transfer (“D2T2”) printing (described further in commonly assigned U.S. Pat. No. 6,066,594, which is incorporated hereto by reference in its entirety.) The information 26a-c can, for example, comprise an indicium or indicia, such as the invariant or nonvarying information common to a large number of identification documents, for example the name and logo of the organization issuing the documents. The information 26a-c may be formed by any known process capable of forming the indicium on the specific core material used.
To protect the information 26a-c that is printed, an additional layer of overlaminate 24 can be coupled to the card blank 25 and printing 26a-c using, for example, 1 mil of adhesive (not shown). The overlaminate 24 can be substantially transparent. Materials suitable for forming such protective layers are known to those skilled in the art of making identification documents and any of the conventional materials may be used provided they have sufficient transparency. Examples of usable materials for overlaminates include biaxially oriented polyester or other optically clear durable plastic film.
The above-described printing techniques are not the only methods for printing information on data carriers such as ID documents. Laser beams, for example can be used for marking, writing, bar coding, and engraving many different types of materials, including plastics. Lasers have been used, for example, to mark plastic materials to create indicia such as bar codes, date codes, part numbers, batch codes, and company logos. It will be appreciated that laser engraving or marking generally involves a process of inscribing or engraving a document surface with identification marks, characters, text, tactile marks—including text, patterns, designs (such as decorative or security features), photographs, etc.
One way to laser mark thermoplastic materials involves irradiating a material, such as a thermoplastic, with a laser beam at a given radiation. The area irradiated by the laser absorbs the laser energy and produces heat which causes a visible discoloration in the thermoplastic. The visible discoloration serves as a “mark” or indicator; it will be appreciated that laser beams can be controlled to form patterns of “marks” that can form images, lines, numbers, letters, patterns, and the like. Depending on the type of laser and the type of material used, various types of marks (e.g., dark marks on light backgrounds, light marks on dark backgrounds, colored marks) can be produced. Some types of thermoplastics, such as polyvinylchloride (PVC), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate (PET), are capable of absorbing laser energy in their native states. Some materials which are transparent to laser energy in their native state, such as polyethylene, may require the addition of one or more additives to be responsive to laser energy.
For additional background, various laser marking and/or engraving techniques are disclosed, e.g., in U.S. Pat. Nos. 6,022,905, 5,298,922, 5,294,774, 5,215,864 and 4,732,410. Each of these patents is herein incorporated by reference. In addition, U.S. Pat. Nos. 4,816,372, 4,894,110, 5,005,872, 5,977,514, and 6179338 describe various implementations for using a laser to print information, and these patents are incorporated herein in their entirety.
Using laser beams to write or engrave information to ID cards presents a number of advantages over conventional printing. For example, the foaming of the thermoplastic that can occur with some types of laser engraving can be adapted to provide an indicium having a tactile feel, which is a useful authenticator of a data carrier that also can be very difficult to counterfeit or alter. In addition, laser engraving generally does not require the use of ink, which can reduce the cost of consumables used to manufacture an ID card. Laser engraving can also be more durable than ink printing, and more resistant to abrasion (which can be particularly useful if a counterfeiter attempts to “rub off” an indicium on an ID card). The resolution and print quality of laser engraving often can be higher than that of conventional ink-based printing. Laser engraving also can be a more environmentally friendly manufacturing process than printing with ink, especially because solvents and other chemicals often used with ink generally are not used with laser engraving.
Despite the advantages of laser engraving, certain limitations still exist. Even when using known laser-enhancing additives, laser marking of some types of materials does not produce an adequate contrast for all applications. Some types of materials, such as silica filled polyolefin, TESLIN core ID documents and TESLIN composite structures (TESLIN is available from PPG Industries, Inc., Pittsburgh, Pa.) using conventional over-laminate materials, are not easily laser engraved. Further, even with use of known laser additives, laser engraving can take too much time and/or too much laser energy to be useful in some manufacturing environments.
Another limitation of laser engraving has been marking speeds. The ability to mark a rastered image via a laser such as a diode pumped YAG laser requires understanding of at least three primary components: materials (e.g., card or other substrate), image information, and laser conditions. AlI three can work together to determine the speed at which an acceptable mark is made via laser engraving/marking. Depending on the speed required and the volume of documents to be made, a certain number of lasers will be needed to engrave the documents. Laser engraving machines are quite costly at present, and despite various improvements made to laser engraving machines to increase speed, laser engraving documents at an acceptable speed and throughput and image quality continues to require, in many instances, multiple laser engraving machines. We have found, however, that by making certain changes to the materials being engraved (which changes are described further herein), it is possible to decrease the time required for laser engraving/marking of images. Decreasing this marking speed can help to increase throughput and may help to reduce the number of laser engraving machines that are required.
In one aspect, we have found that laser engraving of some types of materials, including materials that are not easily engraved (such as laminated TESLIN core ID documents), can be improved by increasing the sensitivity to laser radiation of a laminate used with the material and/or increasing the sensitivity to laser radiation of a coating applied to the material.
One inventive technique disclosed herein improves the material being laser marked or laser engraved by introducing inventive laser enhancing additives to the material. The material can be a laminate, a coating, an article having a laminate or coating formed thereon, and even an image receiving layer/image capable layer that is used for receiving images printed in a manner such as D2T2, laser xerography, inkjet, and mass transfer printing. Components of the laser enhancing additive described herein also can be added, alone or combined with other components, to a series of materials having a laser-receptive optical path between them, to enhance the laser engraving of at least one material in the series. These additives facilitate material sensitivity, greatly improving the ability to laser engrave laminated ID documents. In some embodiments, these additives can also improve the performance of laser engraving even on even those structures (e.g., fused polycarbonate card structures, polyvinylchloride (PVC), polyethylene terephthalate (PET), and acrylonitrile butadiene styrene (ABS)) that can tend to be more easily engraved by laser energy.
The inventors have found that by using the inventive additives described herein, the processing time for polycarbonate and other ID card structures may be decreased. In addition, user of the laser enhancing additives described herein may enable laser engraving to be accomplished using less laser energy and/or lower levels of laser energy than in known methods. Another inventive technique disclosed herein improves the sensitivity of a material being laser engraved by applying a coating to the material, the coating containing at least one laser enhancing additive as described below. The material can be part of virtually any type of article to be laser marked or laser engraved. For example, in one embodiment the material is a core layer in an identification document.
In one embodiment, the additive used to enhance laser engraving comprises a mixture of at least one of copper potassium iodide (CuKI3) or Copper Iodide (CuI) or potassium iodide (KI) or sodium iodide (NaI) or aluminum iodide (AlI) along with at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate (e.g., RSO2Na or R—OSO2Na), and Thioester (e.g., substances containing —SH). This additive can be added to a laminate layer (where the laminate layer itself is to be laser engraved or marked) and/or to a coating (where the surface being coated is to be laser engraved or marked).
Advantageously, in one embodiment, the additive comprises an effective amount of copper iodide, potassium iodide, sodium iodide, aluminum iodide, and zinc sulfide in a host material. The host material can, for example, be a laminate or a coating. The host material also can be another material that is later added to a laminate or coating. The host material can, for example, be a thermoplastic or thermoset. The host material can be a material added or applied to another material to make that material more receptive to another type of printing or marking (e.g., an image receiving layer, such as is disclosed in commonly assigned U.S. Pat. No. 6,066,594, the contents of which are hereby incorporated by reference).
In another advantageous embodiment, the additive comprises an effective amount of any combination thereof of copper iodide, potassium iodide, sodium iodide, aluminum iodide, zinc sulfide, barium sulfide (BaS), alkyl sulfonate (e.g., RSO2Na or R—OSO2Na), and Thioester (e.g., substances containing —SH), in a host material. The host material can, for example, be a laminate or a coating. The host material also can be another material that is later added to a laminate or coating. The host material can, for example, be a thermoplastic or thermoset. The host material can be a material added or applied to another material to make that material more receptive to another type of printing or marking (e.g., an image receiving layer, such as is disclosed in commonly assigned U.S. Pat. No. 6,066,594, the contents of which are hereby incorporated by reference).
For laminates, the host material (as well as the laminate to which the host material may be added) generally can be any material whose laser engraving/marking properties are improved by the addition of the laser enhancing additive described herein, and it is expected that many materials developed in the future will be able to make use of the additive described herein. In at least one embodiment, the addition of the laser enhancing additive described herein enables the laminate to be laser engraved with a grayscale image. In another aspect of the invention, described further herein, we have found that for host materials that are polymers, improving the thermal conductivity of the host material and/or its interpenetrating network (IPN) (e.g., matrices) can help to decrease marking time for laser marking/engraving of images.
In at least one embodiment, the laminate containing the inventive laser enhancing additive can be applied to a layer of material and, after application of heat and pressure to the laminate (e.g., via a platen press), the laminate can comingle with the layer of material enough to actually improve the laser engraving properties of the layer of material that was laminated.
For coatings, in one embodiment, the additive comprises an effective amount of copper potassium iodide and zinc sulfide in a liquid carrier material, which together form a coating that can be applied to an article to be laser engraved. The liquid carrier material can be virtually any known material that can be used as a coating, including resins, polyesters, polycarbonates, vinyls, acrylates, urethanes, and cellulose-base coating. In one embodiment, the liquid carrier material is a material used for coating a surface of a core material (e.g., TESLIN, polycarbonate) of an identification document. The surface being coated generally can be any material (including laminates) whose laser engraving properties are improved by the addition of a coating containing the laser enhancing additive described herein. In at least one embodiment, the addition of the inventive additive to a coating enables the surface to be capable of being engraved with a grayscale image.
For coatings, in another embodiment, the additive comprises an effective amount of at least one of Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), aluminum iodide (AlI), copper potassium iodide, zinc sulfide, and any combination thereof, in a liquid carrier material, which together form a coating that can be applied to an article to be laser engraved. The liquid carrier material can be virtually any known material that can be used as a coating, including resins, polyesters, polycarbonates, vinyls, acrylates, urethanes, and cellulose-base coating. In one embodiment, the liquid carrier material is a material used for coating a surface of a core material (e.g., TESLIN, polycarbonate) of an identification document. The surface being coated generally can be any material (including laminates) whose laser engraving properties are improved by the addition of a coating containing the laser enhancing additive described herein. In at least one embodiment, the addition of the inventive additive to a coating enables the surface to be capable of being engraved with a grayscale image.
In at least one embodiment, the coating containing the inventive laser enhancing laminate can be applied to a layer of material and, after application of heat and pressure to the coating (e.g., via a platen press), the coating can comingle with the layer of material enough to actually improve the laser engraving properties of the layer of material that was coated.
For transparent laminates and/or coatings, the effective amount of the laser enhancing additive can vary depending on the tolerance for possible reduction in the transparency of the laminate or coating. In one embodiment, for transparent laminates or coating, the effective amount of the additive can range from 0.001% by weight up to about 0.1% by weight (based on the total weight of the material to which the additive is added.).
For non-transparent laminates and/or coatings (e.g. colored coatings, colored laminates and/or opaque laminates), the effective amount of the additive can be higher than 1% (e.g., 1%-100%). Those skilled in the art will recognize that the effective amount of the additive for a given use can depend on a number of factors, including the properties of the laminate or coating, the type of laser engraving being performed (e.g., grayscale or non-grayscale), the type of laser used, the desired properties or features of the article or surface being engraved, etc. Advantageously, for at least some transparent laminates and/or coatings used in forming identification documents, the effective amount of the additive is about 0.06% by weight.
In another advantageous embodiment, the constituents of the above-described additive can be present in one or more different layers through which a laser beam can pass. In one example, the copper potassium iodide (or copper Iodide (CuI) or potassium iodide (KI) or sodium iodide (NaI), aluminum iodide (AlI) and any combination thereof) can be present in a first layer of laminate and the zinc sulfide (or barium sulfide (BaS), alkyl sulfonate (e.g., RSO2Na or R—OSO2Na), Thioester (e.g., substances containing —SH) and combinations thereof) can be present in a second layer of laminate, where the first and second layers are either adjacent or separated by one or more layers of material (e.g., another laminate or an adhesive) that is transparent to laser radiation. When a laser beam is directed such that it passes through both of the layers, the combined action of the copper potassium iodide and zinc sulfide enable laser engraving to occur in either or both of the layers. In another example, an effective amount of copper potassium iodide can be present in a coating applied to an article and an effective amount of zinc sulfide can be present in a laminate applied over the coating.
In another example, each of the constituents of the inventive laser enhancing additive (e.g., copper, potassium, iodine, etc.) can be present in a separate layer of coating and/or laminate, where the respective layers are either adjacent or separated by one or more layers of material (e.g., another laminate or an adhesive) that is transparent to laser radiation. When a laser beam is directed such that it passes through all of the layers containing a constituent of the inventive laser enhancing additive, the combined action of the constituents enable laser engraving to occur in at least one of the respective layers. The constituents also can be combined with one or more other constituents, in different layers, in this manner. For example, an effective amount of copper iodide and sodium iodide can be present in a coating applied to an article and an effective amount of zinc sulfide and potassium iodide can be present in a laminate applied over the coating, and an effective amount of aluminum iodide can be present in a coating that is then applied over that laminate. This example is not, of course, limiting; those skilled in the art will appreciate that there are many different ways to combine and/or separate the constituents of the inventive laser enhancing additive into one or more layers of coatings and/or laminates.
In another aspect, the invention provides a composition having laser engraving properties, comprising a host material and an effective amount of a laser enhancing additive. The laser enhancing additive comprises a first quantity of least one of: copper potassium iodide (CuKI3), Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), aluminum iodide (AlI), and any combination thereof, and a second quantity of at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester, and any combination thereof. In one embodiment, the first and second quantities are the same (for example, one part copper iodide and one part barium sulfide). In one embodiment, the first and second quantities are different (for example, three parts potassium iodide to one part zinc sulfide, or 2 parts copper iodide to 4 parts thioester). In one embodiment, the composition is markable by at least one of an excimer, Nd:YAG, and C02 laser (including both light pumped and diode pumped Nd:YAG lasers).
In one embodiment, the laser enhancing additive is present in the composition in an amount from about 0.001 to 0.100 percent by weight based on the total weight of the composition. In one embodiment, the laser enhancing additive is present in an amount between 0.1 percent and 100 percent by weight based on the total weight of the composition. In one embodiment, the laser enhancing additive is present in an amount that is about 0.06 percent by weight based on the total weight of the composition. In one embodiment, the laser enhancing additive comprises 0.03 percent by weight of at least one of copper potassium iodide (CuKI3), Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), Aluminum Iodide (AlI) and any combination thereof, and 0.03 percent by weight of at least one of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester, or any combination thereof, each weight based on the total weight of the composition.
In one embodiment, the host material of the composition is be a material that is not sensitive and/or transparent to laser radiation, such as a material that, by itself, is unable to have acceptable gray scale images laser engraved onto it. The host material can be a laminate or a coating. For example, the host material can comprise at least one of a thermosetting material, thermoplastic, polymer, copolymer, polycarbonate, fused polycarbonate, polyester, amorphous polyester, polyolefin, silicon-filled polyolefin, TESLIN, foamed polypropylene film, polyvinyl chloride, polyethylene, thermoplastic resins, engineering thermoplastic, polyurethane, polyamide, polystyrene, expanded polypropylene, polypropylene, acrylonitrile butadiene styrene (ABS), ABS/PC, high impact polystyrene, polyethylene, polyethylene terephthalate (PET), PET-G, PET-F, polybutylene terephthalate PBT), acetal copolymer (POM), polyetherimide (PEI), polyacrylate, poly(4-vinylpyridine, poly(vinyl acetate), polyacrylonitrile, polymeric liquid crystal resin, polysulfone, polyether nitride, and polycaprolactone, and combinations thereof. In one advantageous embodiment, it has been found that selecting host materials with relatively high degrees of crystallinity (e.g., PET) can help to improve the thermal conductivity of the resultant host material when the inventive laser enhancing additive is added to it.
We have further discovered other techniques for improving thermal conductivity of the host material to improve laser engraving efficiency. In one embodiment, the host material comprises a material having cross-linked functionality. In one embodiment, the host material further comprises a second element, such as a transparent, conductive polymer, such as a cross-linked moiety such as polyurethane, glass beads, glass fibers, and CR-39 (a highly cross-linked thermoset prepared by polymerization of diethylene glycol bis(allyl carbonate) monomer, available from PPG Industries). In one advantageous embodiment, a very low concentration of the second element is blended with the host material. In one advantageous embodiment, the host material comprises at least one of glass beads, glass fibers, and glass threads along with a cross-linking agent.
In one embodiment, the thermal conductivity of the host material is changed by processing the host material to change its orientation and/or density. Those skilled in the art will be familiar with the various types of processes and operations that can operate to change orientation and/or density of a host material.
In at least one embodiment, the invention provides an article of manufacture (such as an identification document) capable of being laser engraved with a grayscale image, comprising a core layer, a first layer and a second layer. The core layer has a first surface. The first layer comprises a first host material, the first host material comprising an effective amount of a first laser enhancing additive comprising at least one of one of copper potassium iodide (CuKI3), Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), Aluminum Iodide (AlI) and any combination thereof. The second layer comprises a second host material and is oriented in relation to the first host material such that a single laser beam can penetrate both at least a portion of the first layer and at least a portion of the second layer. The second host material comprises an effective amount of at least one second laser enhancing additive selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester, and any combinations thereof. The first and second layers are operably coupled to each other and at least one of the first and second layers is operably coupled to the first surface of the core layer. In one embodiment, a grayscale image is laser engraved into at least one of the first and second layers.
In one embodiment, first layer is substantially transparent and the first laser enhancing additive is present in an amount from about 0.001 to 0.100 percent by weight based on the total weight of the first host material. In one embodiment, the second layer is substantially transparent, and the second laser enhancing additive is present in an amount from about 0.001 to 0.100 percent by weight based on the total weight of the second host material. In one embodiment, a third layer is disposed between the first and second layers; the third layer comprises a material that permits transmission of a laser beam therethrough.
In another aspect, the invention provides a method of engraving a material by exposing the material to laser radiation. An effective amount of a laser enhancing additive is added to the material. The laser enhancing additive comprises at least one of copper potassium iodide (CuKI3), Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), Aluminum Iodide (AlI) and any combination thereof, and at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester, and any combinations thereof. The material is exposed to laser radiation in a manner that causes the material to be engraved by the laser radiation. In one embodiment, the effective amount of the laser enhancing additive comprises 0.01% to 0.1% by weight of the material, e.g. 0.06% by weight. In one embodiment, the effective amount of the laser enhancing additive comprises 0.1% to 100% by weight of the material. In one embodiment, an indicium is formed in grayscale in at least a portion of the material through the exposure of the portion of the material to laser radiation. In one embodiment, the laser engraved material is used in the manufacture of an identification document.
In another embodiment, the invention provides a method of laser engraving a grayscale image on an article having first and second layers. A first effective amount of least one of copper potassium iodide (CuKI3), Copper Iodide (CuI), Potassium Iodide (KI), Sodium Iodide (NaI), Aluminum Iodide (AlI) and any combination thereof, is added to the first layer. A second effective amount of at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester, and any combination thereof, is added to the second layer. A laser beam, such as a beam from at least one of an Nd:Yag laser and a CO2 laser, is directed so that it passes through at least a portion of the first layer and at least a portion of the second layer to form a grayscale image in at least one of the first and second layers. In one embodiment, the laser beam is directed so that it that it passes through at least a portion of the first layer and at least a portion of the second layer such that the first and second layers become affixed to each other.
In at least one embodiment, the invention provides a multilayer identification document, comprising a core layer and a film layer. The film layer overlays at least a portion of the core layer and is affixed to the portion of the core layer. The film layer comprising an additive that comprises an effective amount of least one of copper potassium iodide (CuKI3), Copper Iodide (CuI),), Potassium Iodide (KI), Sodium Iodide (NaI), Aluminum Iodide (AlI) and any combination thereof, and an effective amount of at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester, and any combination thereof. In one embodiment, the identification document bears a first indicium thereon, the indicia obtained by exposing the film layer to a laser beam. In one embodiment, the indicia comprises at least one of a gray scale image, photograph, text, tactile text, graphics, information, security pattern, security indicia, and a digital watermark.
In another aspect, the invention provides an identification document having improved laser engraving characteristics. The identification document comprises a TESLIN core coated with a coating containing the laser enhancing additive described above. A grayscale image representing variable data (e.g., personalized data) is laser engraved onto the TESLIN core using an Nd:YAG laser. Optionally, a laminate can be affixed to the TESLIN either before laser engraving or after laser engraving. If the laminate is applied before the TESLIN core is laser engraved, the laminate generally will be transparent to laser radiation.
In one embodiment, the invention provides a composition having laser engraving properties, comprising a host material and a laser enhancing additive. The host material comprises a material, such as a polymer, modified by a first process, whereby the host material as modified by the first process has increased thermal conductivity as compared to the host material before the first process. The laser enhancing additive comprises a first quantity of at least one of copper potassium iodide (CuKI3), Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), and aluminum iodide (AlI), and a second quantity of at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester.
In another embodiment, the invention provides an article of manufacture, such as an identification document, capable of being laser engraved with a grayscale image, comprising a core layer, a first layer, and a second layer. The core layer has a first surface. The first layer comprises a first host material, the first host material comprising a material modified by a first process, whereby the host material as modified by the first process has increased thermal conductivity as compared to the host material before the first process, the host material further comprising an effective amount of a first laser enhancing additive comprising at least one of one of copper potassium iodide (CuKI3), Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), and aluminum iodide (AI). The second layer comprises a second host material, the second layer being oriented in relation to the first host material such that a single laser beam can penetrate both at least a portion of the first layer and at least a portion of the second layer. The second host material comprises an effective amount of a second laser enhancing additive, the second laser enhancing additive selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester. The first and second layers are operably coupled to each other and at least one of the first and second layers is operably coupled to the first surface of the core layer.
In one embodiment, the first process comprises at least one of adding cross linked functionality to the host material, adding a conductive material to the host material, the conductive material being a material that is more thermally conductive than the host material, altering at least a portion of the free volume of the host material, and processing the host material to change at least one of its orientation and density.
In another embodiment, the invention provides a method of engraving a host material by exposing the material to laser radiation. A host material is provided, and a process is performed on the host material such as at least one of adding cross linked functionality to the host material, adding a conductive material to the host material, the conductive material being a material that is more thermally conductive than the host material, altering at least a portion of the free volume of the host material, and processing the host material to change at least one of its orientation and density, to increase the thermal conductivity of the host material. An effective amount of a laser enhancing additive is added to the host material, the laser enhancing additive comprising at least one of copper potassium iodide (CuKI3), Copper Iodide (CuI), potassium iodide (KI), sodium iodide (NaI), and aluminum iodide (AI); and at least one substance selected from the group consisting of zinc sulfide (ZnS), barium sulfide (BaS), alkyl sulfonate, and thioester. The host material is exposed to laser radiation in a manner that causes the material to be engraved by the laser radiation.
Although some companies offer laser engraving document materials, such materials and/or the amount of equipment required to laser engrave such materials (especially for high quality grayscale images on identification documents) can be prohibitively expensive. At least some embodiments of our invention can overcome at least some of these and other limitations of the prior art. At least some embodiments of our invention offer a less expensive option for laser engraving with improved grayscale engraving, and ease of manufacture, without giving up desired security features.
The foregoing and other features and advantages of the present invention will be even more readily apparent from the following Detailed Description, which proceeds with reference to the accompanying drawings.
The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In addition, in the figures, like numbers refer to like elements. Relative dimensions of identification documents, laminate layers, indicia, etc., are provided for illustrative purposes only and are not limiting. Further, throughout this application, laser engraved indicia, information, identification documents, data, etc., may be shown as having a particular cross sectional shape (e.g., rectangular) but that is provided by way of example and illustration only and is not limiting, nor is the shape intended to represent the actual resultant cross sectional shape that occurs during laser engraving or manufacturing of identification documents.